POOL-211
PooledObject#getLastUsed() -> PooledObject#getLastUsedTime() for consistency
Add PooledObject#use() to enable the last use to be tracked
Implement this method in DefaultPooledObject
Plumb in the use of this method to GenericObjectPool

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/pool/trunk@1531310 13f79535-47bb-0310-9956-ffa450edef68